What this season of Game of Thrones lacked in narrative quality, it more than made up for with the sheer number of terrifying ice zombies who tore down a chunk of the Wall on their march to Westeros.

Scenes about the Night King and his army of wights were already good, but they’re so much better when you see the amount of technical artistry that went into bringing them to life. In a new video from El Ranchito, a Spain-based visual effects company, you get a chance to take a look at what all goes into editing the raw footage of Game of Thrones’ actors and sets to make them look like the desolate tundras that have been threatening to overtake the Seven Kingdoms since the first season.